Tap



www?? I im G. E. MILLER.

TAP.V APPLICATION FILI-:D IuIY 7. I9I9.

1,342,754. Patented June 8, 1920.

2 SHEETS-SHEET 2.

WITNESS INVENTOR,

PATENT OFFICE.

GEORGE E. MILLER, OF ETNA, PENNSYLVANIA.

TAI.

Specification of Letters Patent.

Patented June 8, 1920.

Application led July 7, 1919. Serial No. 309,016.

To all Lv/tom it may concern.'

Be it known that I, GEORGE E. MILLER, av citizen of the United States, residing at Etna, in the county of Allegheny and State of Pennsylvania, have invented new and useful Improvements in Taps, of which the following is a specification.

My invention relates to taps, and its object is to produce a tap having inclined or non-radial collapsible cutting dies and constructed to have the requisite strength to prevent the parts thereof from yielding under the strain of heavy work. When such dies are radially movable in the head, it has been found impracticable to provide an axial opening for means for adjusting the dies; but when the dies are movable in nonradial directions, a much larger axial opening is required, which so weakens the head that it yields under the strains of hard work, causing the dies to stick and the tap to become worthless. It is the object of the present invention to make the head with inclined or non-radial adjustable dies and 'a solid axial portion, whereby the head cannot twist or yield while performing its work.

On the accompanying drawings, Figure l is a side elevation of my improved tap; Fig. 2, a central longitudinal section thereof; on the line IIs- II of Fig. 3; Fig. 3, a front ele vation thereof without the front plate or cap g Fig. 4, an enlarged end elevation of a fragment of the tap with the said cap removed; Fig. 5, an elevation of a half of the adjusting nut; Fig. 6, a perspective view of one of the adjusting slides; Fig. 7, a side view of one of the dies; and Fig. 8, a rear view of the cap 17 On the drawings, 1 is the metal base having the holes 2 for screws for attaching the tap to a rotary shaft of a threading machine. 3 is a steel body projecting from the base 1 and arranged at right angles thereto. The end of the body nearest the base 1 is provided with the threads 4 on which the nut 5 works. The nut 5 has toward its outer end the annular internal groove 6. It is divided into lateral halves secured together by screws, one marked 7 being shown.

The body 3 is provided with a number of longitudinal slots 8 open at their forward ends and at the periphery of the body, except at the intermediate portion where the slots are covered by the ring 9 which is welded or brazed to the body. The slots 8 are non-radial or diagonal, that is, they are inclined in the direction in which the head is to be rotated during a cutting operation.

A steel slide 10 is slidable in each slot 8 and has at its inner edge a lateral rib` or lug 11 fitting the undercut slot 12 in the body to prevent the slide from rising in the slot. The base of each slot is parallel with the axis of the body and its sides it the slide closely to prevent any side motion of the slide. The slides lie beneath the ring. The inner end of each slide has the lug 13 arranged in the groove 6, so that, as the nut isturned, the slides will be moved lengthwise.

The forward ends of the slides are beveled on their upper faces and toward their outer ends, and undercut grooves 14 are made in the sides of the slides parallel with the tapered surfaces, the slots lying just above the lug 11.

The threading dies 15 have their sides adapted to fit between the sides of the slots 8, have their bottom edges tapered to correspond with the taper of the wedges, but reversed as to the direction of the taper, and have their sides provided with the ribs 16 fitting the grooves 14e. The outer edges of the dies have the usual thread-cutting faces.

17 is a cap fitting against the outer end of the body 3, to which it is secured by the bolts 18. The inner face of the cap is hollowed out at 19 to provide a clearance for the ends of the slides. The cap has the central internal recess 20 to receive the stopdisk 21 to which the screw 22 working in a hole in the cap is connected. By turning the screw, the disk may be adjusted to stop the outer movement of the slides at such a position as to limit the outward throw of the dies as desired. The adjustment of the disk is fixed by the jam nut 23 on the screw 22.

The ring 9 is provided with the lugs 24 each carrying a cutter 25 for trimming the end of an article at the vconclusion of a thread-cutting operation. The ring 9 also serves to strengthen the tool and hold the slides in place.

It is seen that I have -retained a larger part of the tap-body than is possible when the slides are adjustable by axial rods or taper-pins. The body is weakened only by the slots and they extend far back in the body which adds greatly to the stiii'ness of the tool. It is seen from F ig. 3 that the placing of an axial opening in the body so that a slide therein Could engage the slides would out the body into longitudinal segments and make it Worthless.

I olaim--- l. ln a tap, a body having its inner end threaded and provided with longitudinal grooves inclined in the direction of the rotation oi the tap and having their bases parallel with the Center line of the body, a nut coperable with the threads on the body, slides in the grooves connected to the nut and movable longitudinally thereby, and threading dies adapted to be moved at right angles to the movement of the slides by movement of the slides.

2. In a tap, a body having a solid axial portion, a threaded inner end, and inclined longitudinal grooves having their bases parallel Withthe center line of the body and extending from its outer end into the threaded portion, a nut eoperable With the threads on the body and having an annular groove, slides longitudinally movable in the body grooves and having lugs in the groove in the nut, and threading dies operable by the slides to adjust said dies. 4

B. In a tap, a body having its inner end threaded and provided with longitudinal grooves inclined in the direction of the rotation ofthe tap, a nut Coperable with the threads on the body, slides in the grooves connected to the nut and movable longitudinally thereby, threading dies adapted to be moved at right angles to the movement of the slides by movement of the slides, and a ring inolosing the intermediate portions of the grooves and the slides.

Signed at Pittsburgh, Pa., this 5th day ol" 40 July, A. D. 1919.

GEORGE E. MILLER. 

